Last week, Donald Trump and Hillary Clinton set viewership records for a presidential debate, with 84 million people tuning in.

Tuesday's 9 p.m. ET showdown between vice presidential candidates Mike Pence (the Republican) and Tim Kaine (the Democrat) is unlikely to challenge that record. Unlike last week, the debate is not competing with an NFL football game, but Tuesday is the first day of the Major League Baseball playoffs. (Baltimore Orioles vs. Toronto Blue Jays; first pitch scheduled for 8:08 p.m. on TBS, in the event you want to catch a couple of innings before switching to the debate.)

The format of the debate will be about the same as the presidential debate, but unlike last week's event, Kaine and Pence are not really the people voters are looking to hear from.

Instead, it is likely both of them will have to spend time explaining the controversial positions taken by their running mates. Mr. Pence, what do you make of Donald Trump's pre-dawn tweets about a former Miss Universe? Mr. Kaine, shouldn't the American public be concerned that Hillary Clinton mishandled classified information over email?

Here are a few things to keep in mind about the debate.

Where is it?

Longwood University, about an hour west of Richmond, Va. Longwood was one of dozens of colleges that applied to the Commission on Presidential Debates for the right to host the debate, making its case in part on the strength of an array of debate-related courses the faculty created.

Who are these two guys?

Mike Pence is the governor of Indiana and a former U.S. congressman. During his 10 years in the House of Representatives, Pence chaired the Republican Study Committee, a kind of conservative think tank for the House Republican caucus.

Tim Kaine is a U.S. senator from Virginia who previously served as governor of the state and the mayor of Richmond. Kaine also spent two years as chairman of the Democratic National Committee.

Both VP candidates are younger than their running mates: Kaine is 58, 10 years younger than Clinton; Pence is 57, 13 years younger than Trump.

Neither is well-known, but for what it's worth, Pence is generating on average about 50% more Facebook chatter — likes, shares, comments and posts — than Kaine every week, according to data provided by Facebook. In September, Pence generated an average of 1.3 million interactions per week, while Kaine generated an average of about 925,000. Trump and Clinton are each generating more than 75 million interactions a week.

No third-party candidates?

Nope. Just like the presidential debates, the Libertarian and Green Party did not rank high enough in national polls to qualify for the debate stage.

But, for the record: former Massachusetts governor (and former Republican) William Weld is the Libertarian vice presidential nominee; civil rights activist Ajamu Baraka is the Green Party nominee.

Who is the moderator

Elaine Quijano, an anchor on CBS News' streaming service CBSN, will moderate the debate alone. She is the first Asian-American journalist to moderate a national debate, according to Cosmopolitan. She is a Filipino-American.

When is the next debate?

Tuesday is the only vice presidential debate. The next Trump-Clinton debate is Oct. 9 in St. Louis.

If you want a chance to actually participate in the debates, it is worth noting that a group called the Open Debate Coalition is inviting folks to submit questions for the debates or vote on questions that have already been suggested. The Commission on Presidential Debates and the TV hosts have expressed interest in the results, though there is no real guarantee one of these questions will be asked.

As of this writing, the top questions (most votes) are:

"Would you support requiring criminal background checks for all gun sales?"

"Do you support expanding, and not cutting, Social Security's modest benefits?"